Dry ice storage system



July 7, 1942 F. GOODWIN 2,289,188

DRY ICE STORAGE SYSTEM Filed July 28, 1941 POWER 55 Fig\ 2l Y. 3

F- J'I-EI E Suventor Fran k Goodwin Patented July 7, 1942 DRY ICE STORAGE SYSTEM Frank Goodwin, Seattle, Wash., assignor to Carbon Dioxice & Chemical Co., Seattle, Wash., a

corporation of Delaware Application July 28, 1941, Serial No. 404,336

10 Claims.

It is necessary to store solid carbon dioxide, commonly called dry ice, for appreciable periods of time. During storage it sublimes, and it has been the practice to permit such'sublimed CO2 t0 escape to the atmosphere, since otherwise it would produce a very considerable pressure within the container, and it is not practicable to build such containers or storage receptacles sufilciently strongly to withstand the pressures` which may develop.

This, of course, represents an economic loss, and systems have been devised for withdrawing such sublimed gas, and for compressing it into liquid `form, since the liquid C02 has various commercial uses. The present invention is a system of the latter type, wherein the storage receptacle for the solid carbon dioxide is tight enough to prevent loss of gas, and the sublimed gas, which is heavier than air, and hence collects at thebottomfof the receptacle, is periodically withdrawn therefrom and compressed, or otherwise usefully disposed of.

The principal object of the present invention is to provide a receptacle and system of the character indicated, wherein, as controlled by the L level of the gas withinv the receptacle, withdrawal of sublimed gas is automatically initiated Figure 3 is a simplined diagram, 'similar to Figure 1, showing a modied control system.

It is also an object to devise a control system l for such an arrangement in which a compressor or equivalent withdrawing means is energized, or

'is capable of being energized, as a result of the slight forces generated by the rise and fall of Figure 1 is a diagram inthe nature of a vertical section through such a storage receptacle, illustrating the control means and compressor.

Figure 2 is a simpliiied electrical diagram, i1-l lustrating the control principle incorporated in Figure 1. l

The receptacle for dry ice is designated generally by the numeral I, and it may be subdivided internally by partitions I0 into a number of independent cells, II, I3, and IB, each capable of containing a number of cakes of the solid dry ice S. A suitable cover I2 may be removably secured in place over each cell and preferably these are not gas-tight, that is, they will permit escape of air from above the sublimed gas, as the level of the sublimed gas rises, and reentrance of air to replace the gas withdrawn. The' receptacle I as a whole, and the sever parts thereof, may be suitably insulated, but since they details thereof form no part of this invention, are recognized as necessary, and can be supplied in known manner, they have not been shown in detail, and the insulation shown is merely intended as representative. means of accomplishing insulation of the contents the receptacle as a whole may be sunk within the ground, as shown.

One cell of the receptacle, represented by the cell I3, is not filled with the solid carbon dioxide. Such an empty cell, instead' of forming part of the receptacle I, may be located distant therefrom. and be merely connected thereto. However, it is more convenient to form this cell I3 as an integral part of the receptacle I.

piercing a partition wall near the top thereof,

vand preferably extending downward to a point adjacent the bottom ofA the cell I3. All cells of y the receptacle 'are interconnected for flow of gas from one to the other, and preferably all cells except I3 and I6 are connected at their bottoms, as indicated by theconnection at Iii.` The reason for locating such connections adjacent the bottom of the cells is in` order never to produce intermixture of air and CO2 gas. The air lies above the CO2 gas, and escapes past the cover'IZ as morevCOa gas collects. All C02 gas collecting in any given cell is permitted to escape into other cells by means of the ports l5, and iinally when the receptacle is nearly filled with CO2 gas, this.

gas spills into the cell I 3 by way of the connec- As one It is connected to an adjoining cell I6 by a pipe Il,

withdraw gas from a point adjacent the bottom of the cell, and the compressor is likewise connected to a discharge pipe 2I, and past a cut-off valve 22, to a manifold 23, to which may be connected one or more cylinders C for receiving and containing liquid CO2. The details of the compression system are diagrammatic and representative only, and any suitable means to this' end may be employed, or indeed the withdrawn gas may be otherwise disposed of or conserved.

It is undesirable to permit the compressor 2 to operate continuously. Under some conditions this might withdraw CO2 from the cell I3 at a rate slower than that at which the latter is filled,

and some would be wasted. SinceV it is commercially desirable to retain the product, to the highest degree possible, in the solid form, and in their original shape, it becomes clear that excessive sublimation is to be avoided. It becomes necessary, therefore, to provide control means for the compressor, or for the motor 3 which drives the compressor, so that the compressor operates only when there is in cell I3 an accumulated sup-` ply of gaseous CO2, and stops when the level of gaseous CO2 in cell I3 has been lowered to a desired point.

It must be remembered that gaseous CO2 is heavier than air. While it might be considered that these two gases, if both are present'in the same space, will mingle by diffusion, and while this is true to a slight extent, particularly if there is anyappreciable turbulence, nevertheless the two gases will remain separate, in the absence of turbulence, to a very appreciable degree, and for considerable periods. There will be a plane of separation between them in the nature of a rather indistinct boundary, one not so sharply defined as the boundary between oil and water, or air 'and water, but nevertheless a boundary, below which the atmosphere is principally CO2 gas, and above which the atmosphere is principally air. Ittherefore becomes possible to provide a float, one which is buoyant upon the heavier CO2 gas, but which is not buoyant in air, which float will remain'in the zone of this boundary, and which will rise and fall as the boundary rises and falls.

Such a float is indicated at 4 within thecell I3. It may be considered as a balloon, filled with a gas sutllciently light to counteract its mass and to maintain its oating upon the surface oi' the CO2 gas, yet not aiording lit so much buoyance as to c ause it to rise in the air,l but rather to remain at the bottom of the air within the cell. This iloat or balloon may be conveniently made of Cellophane, and might be lled with hydrogen gas or some other light gas, and it mayl be suitably counterweighted. The vertical guide cups 4o, which are attached to the naar 4, may

constitute such a counterweight. Preferably the float is guided, as bythe rods 4I, for vertical movement in a given path within the cell or chamber I3.

Since this iloat remains always at the bound-V ary between the air in the upper part of the cell and the gaseous carbon dioxide in the bottom thereof, it is possible to employ this float, firstm` as a means to indicate the level of CO2 and there.:

matic operation of the compressor may be employed. In Figures v1 and 2 I have shown such a control'actuated by means of photo-electric cells. An upper cell 5 may be normally illuminated by a lamp 5I, and a lower cell 50 may be illuminated and energized by a lamp 52. The path of the balloon or float 4 is arranged to interrupt each of these beams, and the particular one which is interrupted depends upon the vertical position of the float, and therefore the level of the gaseous CO2 within the cell I3. This effect may be advanced, and the action made more decisive, by banding the equator of the float 4 with-,a dark-colored band, as indicated at 42.

Asmay be observed best in Figure 2, the cells 5 and 50 are connected by suitable circuit means to a control device, which in Figure l is represented at 6. Within this'control device is provided a switch in the circuit to the motor 3, consisting, for example, of the xed contact point 30 and the movable arm 3 I. Light centering springs 32 tend to retain the switch arm A 3I in neutral position except as they are overcome and the arm is pulled into contact with the switch point 30 by a relay 63 in circuit with the cell 50, or is pulled to a switch-open position by the relay 62 in circuit with the cell 5.

It will now be clear that the cell I6 will collect gas owing from all the other cells II, and the gas within the cell I6 will overflow into the cell I3. As the CO2 gas collects in the bottom of the cell I3 the boundary of separation between the `CO2 gas and the air rises, and with it rises the float 4, until the iloat interrupts the light beam between the source 5I and the cell 5. This deenergizes the relay 62, but since the cell 50 is still energized its relay 63 pulls the switch arm 3| into contact with the switch point 3U, and energizes the motor 3. Energization of the motor initiates operation of the compressor, which withdraws gas by way of the pipe 20, to be replaced by inilowing air entering at the top of cell I3, and discharges the CO2 gas in condensed liquid form by way of the pipe 22 into a suitable receptacle, indicated at C. The level ofthe CO2 gas drops, and the float 4 drops withit, but even though the beam from the light source 5I to the cell 5 is reestablished the switch arm 3I remains in contact with the terminal 30. The relay 63 may indeed be a self-holding relay to this' end if need be; the showing of Figure 2 is purely rep'- resentative, and such ampliers or relays as may be found necessary would be employed. When the float 4 drops to a level to interrupt the beam from the source 52 to the cell 5I'the relay 63 is immediately deenergized, and the switch arm 3| is positively pulled away from the xed terminal 30, breaking the motor circuit. Operation of the compressor thereupon ceases, and is not resumed until, through the gradual process of collection of the gas in the bottom of the cells I I and I8, and its overflow into cell I3, enough has collected to warrant its withdrawal, which occurs when the float 4 again interrupts the beam be tween the source 5I and the cell 5.

In the alternative arrangement shown dagrammatically in Figure 3 the iloat itself is provided with contacts 53 and 54, which are in the circuit of a relay 55. Current is supplied to the contact 53 or 54 through the guide ferrules 49 from a conducting counterweight cord 43, extending over guide pulleys 44 and supporting a counterweight 45. Upon contact of the terminals 53 or 54 with one or the other of the xed termlnals 56 or 51 at top and bottom of the cell 1. A storage plant for solid carbonv dioxide comprising a suitable receptacle, a compressor connected thereto to withdraw CO2 gas, a iioat' 'within said receptacle buoyant upon CO2 gas but not in air. and hence niovable vertically asv the level of CO2 gas rises or falls,l and means operatively connected to the compressor, and arranged for automatic actuation when the float reaches a selected upper level to initiate operation of the compressor for withdrawal of CO2 gas.

2. A storage plant for solid carbon dioxide comprising a suitable receptacle, a compressor connected thereto to withdraw CO2 gas, a float within said receptacle buoyant upon CO2 gas but notin air, and hence movable vertically as the level of CO2 gas rises or falls, and means `operatively connected to the compressor, and arranged for automatic actuation when the iioat reaches a selected upper level to initiate operation of the compressor for withdrawal of CO2 gas, and also arranged for automatic actuation when the iioat reaches a selected lower level to discontinue operation of the compressor.

3. A storage plant vior solidv carbon. dioxide CO2-gas therein rises or falls, and means energizable automatically at selected upper and lower limits of the iioat's movement to appropriately govern said .actuating means. and thereby to maintain the CO2 gas level between such limits.

6. Means to effect the withdrawal of sublimed CO2 gas from a storage receptacle for solid carbon dioxide, comprising a compressor or the like connected to such receptacle for withdrawal therefrom, ka float withinthe receptacle which is buoyant upon C02 gas butnot in air, arid hence is movable vertically as the level of CO: Y

gas rises and falls, and vmeans operatively connected to the compressor, and arranged for automatic actuation when the oat reaches a selectved upper and a selected lower limit, to auto- =`niatically initiate and discontinue operation, re-

spectively, of said compressor.

7.l Means to eiie'ct the withdrawal o f sublimed CO2 gas from 'a storage receptacle for solid carbon dioxide, comprising a compressor or the like connected to such receptacle for withdrawal therefrom, a float within the vreceptacle which is buoyant upon CO2 gas but not in air, and hence is movable vertically as the level of C02 gas rises and falls, two-circuit means, one at a selected upper limit oi movement of the float and the other at a selected lower limit of its movement, both operatively connected to the compressor, said circuit means being respectively energizable by the float as it reaches such limits, and being arranged, the upper one to automatically initiate operation of the compressor` and the lower one to automatically discontinue such operation.

8. Ih'el combination of' claim 7, whereinl each of the circuit means includes a photo-sensitive cell and a light source to illuminate the same.

comprising a suitable receptacle, a compressor connected thereto to withdraw CO2 gas, a oat within said receptacle buoyant upon CO2 gas but not in air, and hence movable vertically as the level of CO2 gas rises or falls, means operatively connected to the compressor, and arranged for automatic actuation when the oat reaches a selected upper level to initiate operation of the compressor for withdrawal of C02 gas, and further means operatively connected to the compressor, and arranged for automatic actuation when the oat reaches a selected lower level to discontinue operation of the compressor.

4. A storage plant forl solid carbon dioxide comprising a suitable receptacle, a compressor connected thereto towithdraw CO2 gas, a float within said receptacle buoyant upon CO2 gas but not in air, and hence movable vertically as the level of CO2 gas rises or falls, means operatively connected to the compressor to initiate and means guiding the float to interrupt the light beam o! the respective cells at the corresponding limits of its vertical movement. and means controlled by the respective cells to energize or to deenergize the compressor.

9. The combination of claim 7,- including a .vertical guide for the float, and wherein each of the circuit means includes afcontact disposed respectively at the upper and lower limits of the floats movement, a common contact carried by the iioat, and included in each oi' said i circuit means, and compressor control means .energizable upon contact of the common contact with the upper contact to energize the compressor, and upon contact of the common contact with the lower contact to deenergize the Compressor.

operation thereof for withdrawal of CO2 gas,

and further means operatively connected to the ,compressor, and arranged for automatic actuation when the oat reaches a selected lower level to discontinue operation of the compressor.

5. A storage plant for solid carbon dioxide comprising a suitable receptacle, acompressor connected to the receptacle to withdraw CO2 z gas, actuating means to initiate and to terminate operation of the compressor, and control means for said actuating means including a float buoyant upon CO: gas but not in air, movable vertically within said receptacle as the level of l0. The combination of claim "l, including a vertical guide for the iiat, and wherein each of the circuit means-includes a contact disposed respectively at the upper and lower limits of the fioats movement, a common contact carried by the oat, and included in each of said circuit means, a counterweight and supporting cord connected to the iioat, said cord constituting' the electric lead to said common contact, and compressor control means energizable upon contact of the common contact with the upper contact to energize the compressor, and upon contact of the common contact with the lower contact to deenergize the compressor.

'FRANK GOODWIN. 

